Method for marking defect and device therefor

Abstract

The defect marking method comprises the steps of: installing a surface defect tester to detect surface flaw and a marker device to apply marking at defect position, in a continuous processing line of steel sheet; detecting the surface flaw on the steel sheet using the surface defect tester; determining defect name, defect grade, defect length, and defect position in the width direction of the steel sheet, on the basis of thus detected flaw information, further identifying the defect in terms of harmful defect, injudgicable defect, and harmless defect; applying tracking of the defect position for each of the harmful defect and the injudgicable defect; and applying marking to the defect position. The defect marking device comprises a defect inspection means having plurality of light-receiving parts and a signal processing section, and a marking means.

1. A method for marking a defect, comprising the steps of:
 (a) arranging a surface defect tester to detect a surface flaw and an ink marker device having a felt impregnated with ink to mark the defect at a defect position, in a continuous processing line of a steel sheet; 
 (b) detecting the surface flaw on the steel sheet using the surface defect tester; 
 (c) determining a defect name, defect grade, defect length, and defect position in a width direction of the steel sheet, on the basis of information regarding the detected surface flaw, and identifying the surface defect in terms of harmful defect, injudicable defect, and harmless defect; 
 (d) tracking the defect position for each harmful defect and injudicable defect; 
 (e) marking the surface defect at the defect position by pressing the felt on the steel sheet to fix the ink on the surface of the steel sheet when the defect reaches the ink marker device; 
 arranging an internal defect tester to detect a defect inside of the steel sheet; and 
 determining the defect length and the defect position in the width direction of the steel sheet, on the basis of the detected flaw information, and identifying the defect in terms of harmful defect and harmless defect, 
 wherein the step of marking comprises changing a defect marking position based on the defect information in the width direction of the steel sheet, given by the surface defect tester and the internal defect tester, and marking the defect. 
 
     
     
       2. The method of  claim 1 , wherein the step of identifying the defect comprises identifying harmful defect, injudicable defect, and harmless defect, based on the defect name, the defect grade, the detect length, the defect position in the width direction of the steel sheet, and a use of the steel sheet. 
     
     
       3. The method of  claim 1 , wherein the step of identifying the defect in terms of harmful defect and harmless defect comprises identifying the harmful detect and harmless defect, based on the defect length, the defect position in the width direction of the steel sheet, and a use of the steel sheet. 
     
     
       4. A method for marking a defect, comprising the steps of:
 (a) arranging a surface defect tester to detect a surface flaw and a marker device to mark the defect at a defect position, in a continuous processing line of a steel sheet; 
 (b) detecting the surface flaw on the steel sheet using the surface defect tester; 
 (c) determining a defect name, defect grade, defect length, and defect position in a width direction of the steel sheet, on the basis of information regarding the detected flaw, and identifying the surface defect in terms of harmful defect, injudicable detect, and harmless defect; 
 (d) tracking the defect position for each harmful defect and the injudicable defect; 
 (e) marking the defect to the defect position when the defect reaches the marker device; and 
 (f) re-judging a defect which is identified as an injudicable defect using the surface defect tester to identify harmful defect and harmless defect by an inspector. 
 
     
     
       5. The methodg of  claim 4 , wherein the step of re-judging a defect comprises:
 generating an alarm regarding a defect that is identified by the surface defect tester as an injudicable defect; 
 automatically reducing a travelling speed of the steel sheet; and 
 re-judging the injudicable defect by an inspector. 
 
     
     
       6. The method of  claim 4 , wherein the step of re-judging a defect comprises:
 generating a display image of the detect and a display image of the defect position for a defect that is identified as an injudicable defect by the surface defect tester; and 
 re-judging the injudicable defect by an inspector. 
 
     
     
       7. The method of  claim 1 , wherein the step of marking further comprises changing the defect marking position depending on use of the steel sheet, and marking the defect. 
     
     
       8. The method of  claim 1 , wherein the step of marking further comprises identifying harmful defect and injudicable defect, and marking the defect. 
     
     
       9. The method of  claim 1 , wherein the step of marking further comprises marking with a different color for each of a plurality of steel sheet grades. 
     
     
       10. A method for marking a defect comprising the steps of:
 (a) arranging a surface defect tester to detect a surface flaw and an ink marker device having a felt impregnated with ink to mark the defect at a defect position, in a continuous processing line of a steel sheet; 
 (b) detecting the surface flaw on the steel sheet using the surface defect tester; 
 (c) determining a defect name, defect grade, defect length, and defect position in a width direction of the steel sheet, on the basis of information regarding the detected surface flaw, and identifying the surface defect in terms of harmful defect, injudicable defect, and harmless defect; 
 (d) tracking the defect position for each harmful defect and injudicable defect; 
 (e) marking the surface defect at the defect position by pressing the felt on the steel sheet to fix the ink on the surface of the steel sheet when the defect reaches the ink marker device; and, 
 (f) arranging a defect marking detection device at a downstream side of the ink marker device and monitoring a marking state, 
 wherein the step of monitoring comprises changing a threshold value of the defect marking device depending on a grade of the steel sheet and monitoring the marking state. 
 
     
     
       11. The method of  claim 1 , further comprising the step of arranging the marker device and a defect marking detection device as a set, and letting these devices track the defect marking position, and monitoring a marking state. 
     
     
       12. The method of  claim 1 , further comprising the step of arranging an ink drying device at a downstream side of the ink marker device. 
     
     
       13. The method of  claim 1 , further comprising the step of installing the ink marker device, a defect marking detection device, and an ink drying device, as a set, and letting these devices track the defect marking position, and monitoring a marking state. 
     
     
       14. The method of  claim 1 , wherein the step of identifying harmful defect, injudicable defect, and harmless defect comprises identifying harmful defect, injudicable defect, and harmless defect, by changing a threshold value for each of the harmful defect and the harmless defect depending on a use of the steel sheet. 
     
     
       15. The method of  claim 1 , further comprising the steps of:
 arranging a defect marking detection device at a downstream side of the marker device to detect defect information; and 
 reflecting the detected detect information on a defect removing action. 
 
     
     
       16. A method for marking a defect comprising the steps of:
 arranging a surface defect tester to detect a surface flaw and an ink marker device having a felt impregnated with ink to mark the defect at a defect position, in a continuous processing line of a steel sheet; 
 detecting the surface flaw on the steel sheet using the surface defect tester; 
 determining a defect name, defect grade, defect length, and defect position in a width direction of the steel sheet, on the basis of information regarding the detected surface flaw, and identifying the surface defect in terms of harmful defect, injudicable defect, and harmless defect; 
 tracking the defect position for each harmful defect and injudicable defect; 
 marking the surface defect at the defect position by pressing the felt on the steel sheet to fix the ink on the surface of the steel sheet when the defect reaches the ink marker device; 
 arranging a defect marking detection device and a cleaning device at a downstream side of the ink marker device; 
 reflecting the defect information detected by the defect marking detection device on a defect removing action; and 
 re-judging the injudicable defect by an inspector, and, in the case where the defect is judged a harmless defect, cleaning the marking ink with the cleaning device. 
 
     
     
       17. The method of  claim 1 , wherein the ink marker device is an abrasive member marker device. 
     
     
       18. A method for producing a defect-marked steel coil, comprising the steps of:
 providing a defect-detecting device which detects a defect and an ink marker device having a felt impregnated with ink in a continuous processing line of a steel sheet; 
 determining a harmful defect based on a signal from the defect detecting device; and 
 marking the harmful defect at a defect-detected position on the steel sheet by pressing the felt on the steel sheet to fix the ink on a surface of the steel sheet, when the harmful defect reaches the marker device, 
 wherein the pressing of the felt is carried out by pressing the felt on the steel sheet with a pressing force of 100 to 500 g. 
 
     
     
       19. The method of  claim 18 , wherein the defect-detecting device is at least one device selected from the group consisting of a surface-defect detecting device and an internal-defect detecting device. 
     
     
       20. The method of  claim 18 , wherein marking the harmful defect comprises:
 setting a marking length so as to cover the harmful defect; and 
 marking the harmful defect. 
 
     
     
       21. The method of  claim 18 , wherein the ink is removable by a weak alkali cleaning agent. 
     
     
       22. The method of  claim 18 , wherein marking the harmful defect comprises marking the harmful defect with a line having a width of from 3 to 10 mm. 
     
     
       23. The method of  claim 18 , wherein determining the harmfuldefect comprises:
 detecting defect candidates by using the defect-detecting device; 
 identifying defect grades based on the signal from the defect-detecting device; and 
 classifying each of the defect candidates as being either harmful or harmless. 
 
     
     
       24. The method of  claim 18 , wherein determining the harmful defect comprises:
 detecting defect candidates by using the defect-detecting device; 
 identifying defect grade and defect length based on the signal from the defect-detecting device; and 
 classifying each of the defect candidates as being either harmful or harmless. 
 
     
     
       25. The method of  claim 18 , wherein:
 determining the harmful defect comprises classifying a defect candidate as being either harmful, unjudgeable, or harmless; and 
 marking the harmful defect comprises marking the harmful defect, or an unjudgeable defect, at the defect-detected position on the steel sheet, when the harmful defect or the unjudgeable defect reaches the marker device. 
 
     
     
       26. The method of  claim 18 , further comprising:
 providing a defect-marking detection device on a downstream side of the marker device; and 
 confirming a marking condition using the defect-marking detection device. 
 
     
     
       27. A method for producing a defect-marked steel coil, comprising the steps of:
 feeding a steel coil having information regarding an identified harmful defect into a continuous processing line of a steel sheet, said continuous processing line including an ink marker device having a felt impregnated with ink; and 
 marking the harmful defect based on the information regarding the identified harmful defect by pressing the felt on the steel sheet to fix the ink on a surface of the steel sheet, when the harmful defect reaches the marker device, 
 wherein the pressing of the felt is carried out by pressing the felt on the steel sheet with a pressing force of 150 to 500 g. 
 
     
     
       28. The method of  claim 27 , wherein marking the harmful defect comprises:
 setting a marking length so as to cover the harmful defect; and 
 marking the harmful defect. 
 
     
     
       29. The method of  claim 27 , wherein the ink is removable by a weak alkali cleaning agent. 
     
     
       30. The method of  claim 27 , wherein marking the harmful defect comprises marking the harmful defect with a line width of from 3 to 10 mm. 
     
     
       31. The method of  claim 27 , wherein said steel coil is a steel coil whose candidate defects were detected using at least one device selected from the group consisting of a surface-defect detecting device and an internal-defect detecting device, and wherein the candidate defects were classified as being either harmful or harmless based on a signal from said at least one device. 
     
     
       32. The method of  claim 27 , wherein said steel coil is a steel coil whose candidate defects were detected using at least one device selected from the group consisting of a surface-defect detecting device and an internal-defect detecting device, wherein a defect grade and defect length were identified based on a signal from the defect-detecting device, and wherein the candidate defects were classified as being either harmful or harmless. 
     
     
       33. The method of  claim 27 , wherein:
 said steel coil is a steel coil whose defects were classified as being either harmful, unjudgeable, or harmless; and 
 marking the harmful defect comprises marking the harmful defect or an unjudgeable defect, at a defect-detected position on the steel sheet, when the harmful defect or the unjudgeabte defect reaches the marker device. 
 
     
     
       34. The method of  claim 27 , further comprising:
 providing a defect-marking detection device on a downstream side of the marker device; and 
 confirming a marking condition using the defect-marking detection device. 
 
     
     
       35. A defect-marked steel coil, having a mark made by marking a harmful defect at a defect position on a steel sheet by pressing a felt impregnated with ink on the steel sheet to fix the ink on a surface of the steel sheets,
 wherein the felt is pressed to the steel sheet with a pressing force of 100 to 500 g. 
 
     
     
       36. The defect-marked steel coil of  claim 35 , wherein said mark has a marking length so as to cover the harmful defect. 
     
     
       37. The defect-marked steel coil of  claim 35 , wherein the ink is removable by a weak alkali cleaning agent.